Mallory Mativenga

Circuits implemented with high-performance amorphous-indium-gallium-zinc-oxide thin-film transistors (TFTs) are realized on polyimide/polyethylene-terephthalate plastic substrates. The TFTs on plastic exhibit a saturation mobility of 19 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /V·s and a gate voltage swing of ~0.14 V/dec. For an input of 20 V, an 11-stage ring oscillator operates at 94.8 kHz with a propagation delay time of 0.48 μs

We present here an amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) in which the accumulation layer is not only confined to the a-IGZO/gate-insulator interface, but extends the entire depth of the a-IGZO. This bulk accumulation TFT is achieved by the use of top- and bottom-gate, that are electrically tied together, resulting in drain current that is over seven times higher than that of a single-gate device, for an a-IGZO thickness of 10 nm. Thus, high drive current is achi

Major obstacles toward the manufacture of transparent and flexible display screens include the difficulty of finding transparent and flexible semiconductors and electrodes, temperature restrictions of flexible plastic substrates, and bulging or warping of the flexible electronics during processing. Here we report the fabrication and performance of fully transparent and rollable thin-film transistor (TFT) circuits for display applications. The TFTs employ an amorphous indium-gallium-zinc oxide se

Radiating amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) with deep ultraviolet light (λ = 175 nm) is found to induce rigid negative threshold-voltage shift, as well as a subthreshold hump and an increase in subthreshold-voltage slope. These changes are attributed to the photo creation and ionization of oxygen vacancy states (V_O), which are confined mainly to the top surface of the a-IGZO film (backchannel). Photoionization of these states generates free electrons and the t

A hump in the subthreshold regime of the transfer characteristics is reported for amorphous-indium-galium-zinc-oxide thin-film transistors (TFTs) when they are exposed to large positive gate bias-stress. As stress time progresses, transfer characteristics shift in two opposite directions; the main transistor shifts in the positive, while the hump shifts in the negative gate-voltage direction. The hump occurs at the same current level in all TFTs with channel widths ranging from 10 to 200 μm, whi

Amorphous-InGaZnO4 (a-IGZO) thin-film transistors (TFTs) on glass undergo large positive threshold voltage shifts (ΔVTH) under high current stress (HCS)—a consequence of Joule heating of the active-layer. Here, we show that when the active layer is split into smaller parts, HCS induces negligible ΔVTH. When the active layer heats up during HCS, conducting electrons in the channel gain enough energy to surmount the energy barrier at the active-layer/gate-insulator interface and become trapped int

We report the effect of the drain-offset length on the performance of amorphous-indium–gallium–zinc–oxide (a-IGZO) thin-film transistors (TFTs). While the field-effect mobility decreases from <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\sim$</tex> </formula> 40 to 10 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="

Highly stable amorphous indium–gallium–zinc-oxide (a-IGZO) thin-film transistors (TFTs) were fabricated with an etch-stopper and via-hole structure. The TFTs exhibited 40 cm2/V s field-effect mobility and a 0.21 V/dec gate voltage swing. Gate-bias stress induced a negligible threshold voltage shift (Δ V th) at room temperature. The excellent stability is attributed to the via-hole and etch-stopper structure, in which, the source/drain metal contacts the active a-IGZO layer through two via holes

Abstract We have reviewed the comparison of LTPS and Oxide TFTs for AMOLED backplane application. The device performance and stability of ELA based LTPS TFTs are excellent even though the process cost is much higher than that of oxide TFTs. Oxide TFTs, on the other hand, can be manufactured with lost cost and the device performance is good enough for large‐area AMOLED backplane. However, run‐to‐run reproducibility and bias stability of oxide TFTs are much inferior to those of their LTPS counterp

Stable and fast-switching thin-film transistors and circuits incorporating 5-nm-thick amorphous-InGaZnO (a-IGZO) active layers are demonstrated, and their dependence on channel length is studied. Turn-on voltage shifts in the positive gate voltage direction as the channel length increases. A low area density of defects in the bulk a-IGZO, which is ultrathin, results in good stability under positive bias stress, whereas interdiffusion of electrons/electron donors from the highly doped source and

We employ a circular (Corbino) thin-film transistor (TFT) structure, in which the outer-ring is the drain and the inner-ring is the source, to improve the stability of amorphous-indium-gallium- zinc-oxide TFTs under tensile bending strain. We attribute the stability improvement to a more uniform electric field distribution across the circular channel, as it is isolated from local electric field crowding at sharp corners or channel edges. In addition, the effect of strain-induced increase in chan

We report a low-voltage-driven amorphous indium-gallium-zinc oxide (a-IGZO) semiconductor-based Corbino (circular) thin-film transistor (TFT) with infinite output resistance beyond pinchoff. The Corbino TFT has inner and outer concentric ring electrodes, and when the latter is the drain, channel width (W) decreases with channel length (L), such that the W/L ratio is not changed after pinchoff. As demonstrated herein, this a-IGZO Corbino TFT is, therefore, a good candidate for uniform current dri

Despite their potential use as pixel-switching elements in displays, the bias and light instability of mixed oxide semiconductor thin-film transistors (TFTs) still limit their application to commercial products. Lack of reproducible results due to the sensitivity of the mixed oxides to air exposure and chemical contamination during or after fabrication hinders any progress towards the achievement of stable performance. Consequently, one finds in literature several theories and mechanisms, all ju

Abstract Despite the widespread research on organic–inorganic hybrid perovskites, the ambient air instability and ion migration‐induced hysteresis in the current–voltage characteristics of their devices remain unsolved. Here, it is shown that stable ambient air operation of methylammonium lead iodide (MAPbI 3 ) thin‐film transistors can be achieved by solution processing of the MAPbI 3 film in ambient air via solvent engineering. N , N ‐dimethylformamide (DMF), mixed with dimethyl sulfoxide (DMS